Android中的Service使用

Service的生命周期（适用于2.1及以上）

1. 被startService的
无论是否有任何活动绑定到该Service，都在后台运行。onCreate(若需要) -> onStart(int id, Bundle args). 多次startService，则onStart调用多次，但不会创建多个Service实例，只需要一次stop。该Service一直后台运行，直到stopService或者自己的stopSelf()或者资源不足由平台结束。

2. 被bindService的
调用bindService绑定，连接建立服务一直运行。未被startService只是BindService，则onCreate()执行，onStart(int,Bundle)不被调用；这种情况下绑定被解除，平台就可以清除该Service(连接销毁后，会导致解除，解除后就会销毁)。

3. 被启动又被绑定
类似startService的生命周期，onCreate onStart都会调用。

4. 停止服务时
stopService时显式onDestroy()。或不再有绑定(没有启动时)时隐式调用。有bind情况下stopService()不起作用。

以下是一个简单的实现例子，某些部分需要配合logcat观察。
AcMain.java

package jtapp.myservicesamples;
import android.app.Activity;
import android.content.ComponentName;
import android.content.Context;
import android.content.Intent;
import android.content.ServiceConnection;
import android.os.Bundle;
import android.os.IBinder;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.Toast;
public class AcMain extends Activity implements OnClickListener {
private static final String TAG = "AcMain";
private Button btnStart;
private Button btnStop;
private Button btnBind;
private Button btnExit;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
findView();
}
private void findView() {
btnStart = (Button) findViewById(R.id.Start);
btnStop = (Button) findViewById(R.id.Stop);
btnBind = (Button) findViewById(R.id.Bind);
btnExit = (Button) findViewById(R.id.Exit);
btnStart.setOnClickListener(this);
btnStop.setOnClickListener(this);
btnBind.setOnClickListener(this);
btnExit.setOnClickListener(this);
}
@Override
public void onClick(View v) {
Intent intent = new Intent("jtapp.myservicesamples.myservice");
switch(v.getId()) {
case R.id.Start:
startService(intent);
Toast.makeText(this,
"myservice running " + MyService.msec/1000.0 + "s.",
Toast.LENGTH_LONG).show();
break;
case R.id.Stop:
stopService(intent);
Toast.makeText(this,
"myservice running " + MyService.msec/1000.0 + "s.",
Toast.LENGTH_LONG).show();
break;
case R.id.Bind:
bindService(intent, sc, Context.BIND_AUTO_CREATE);
break;
case R.id.Exit:
this.finish();
break;
}
}
private MyService serviceBinder;
private ServiceConnection sc = new ServiceConnection() {
@Override
public void onServiceDisconnected(ComponentName name) {
Log.d(TAG, "in onServiceDisconnected");
serviceBinder = null;
}
@Override
public void onServiceConnected(ComponentName name, IBinder service) {
Log.d(TAG, "in onServiceConnected");
serviceBinder = ((MyService.MyBinder)service).getService();
}
};
@Override
protected void onDestroy() {
//this.unbindService(sc);
//this.stopService(
// new Intent("jtapp.myservicesamples.myservice"));
super.onDestroy();
}
}

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main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="fill_parent"
android:layout_height="fill_parent">
<TextView android:layout_width="fill_parent"
android:layout_height="wrap_content" android:text="@string/hello" />
<Button android:text="Start MyService" android:id="@+id/Start"
android:layout_width="wrap_content" android:layout_height="wrap_content"/>
<Button android:text="Stop MyService" android:id="@+id/Stop"
android:layout_width="wrap_content" android:layout_height="wrap_content"/>
<Button android:text="Bind MyService" android:id="@+id/Bind"
android:layout_width="wrap_content" android:layout_height="wrap_content"/>
<Button android:text="Exit AcMain" android:id="@+id/Exit"
android:layout_width="wrap_content" android:layout_height="wrap_content"/>
</LinearLayout>

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MyService.java

package jtapp.myservicesamples;
import android.app.Service;
import android.content.Intent;
import android.os.Binder;
import android.os.IBinder;
import android.util.Log;
public class MyService extends Service {
private static final String TAG = "MyService";
public static long msec = 0;
private boolean bThreadRunning = true;
private final IBinder binder = new MyBinder();
public class MyBinder extends Binder {
MyService getService() {
return MyService.this;
}
}
@Override
public IBinder onBind(Intent intent) {
return binder;
}
@Override
public void onCreate() {
new Thread(new Runnable(){
@Override
public void run() {
while (bThreadRunning) {
try {
Thread.sleep(100);
} catch (InterruptedException e) {
}
Log.i(TAG, "myservice running " + (msec+=100) + "ms.");
}
}
}).start();
}
@Override
public void onDestroy() {
bThreadRunning = false;
super.onDestroy(); // 可以不用
}
}

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AnndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="jtapp.myservicesamples" android:versionCode="1"
android:versionName="1.0">
<application android:icon="@drawable/icon" android:label="@string/app_name"
android:debuggable="true">
<activity android:name=".AcMain" android:label="@string/app_name">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<service android:name="MyService">
<intent-filter>
<action android:name="jtapp.myservicesamples.myservice"></action>
</intent-filter>
</service>
</application>
</manifest>

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